Technical Abstract:
The sweetpotato is the seventh largest food crop in the world. Up to 98% of the production is in developing countries, where much of the crop is lost to insect pests. The USDA/Clemson University sweetpotato breeding program has developed several advanced clones and cultivars with multiple resistances to 13 insect species, including the WDS complex (Wireworm, Diabrotica, Systena) and the sweetpotato weevil (SPW). Previous research has shown a high genetic correlation in our germplasm between resistance to the WDS complex and the SPW. Our current goal is to develop cultivars with higher resistances to these pests and to combine these higher resistances with the needed horticultural traits. Our approach is to accelerate the selection process for insect resistances by using both insect bioassays and laboratory quantification of the biochemical compounds involved in resistance. Our hypothesis is that the USDA/Clemson University clones have ea general mechanism conditioning insect resistance. The results of bioassays suggest that this general resistance is a type of antibiosis conferred by the presence of resin glycosides, which dramatically reduce larval growth and survival. The efficacy of the multiple pest resistance present in the USDA/Clemson University clones is being tested against local insect pests in Jamaica and Uganda.